Currently, radiating pylons having large dimensions are used to transmit high levels of power in medium-frequency bands. The disadvantage of these pylons is that they are expensive, they require a significant amount of secure land for their installation, and they are not very aesthetically pleasing and are relatively obtrusive. They are not optimized for broadcasting substantially via surface waves.
Antennas using only one surface wave as a propagation vector are very few in number. Current surface-wave systems use whip or biconical antennas, which are not very suitable for radar applications.
Radiating pylons, and generally all antennas having vertical polarization, for example of the whip or biconical kind, substantially generate a space-wave field (also known as ionospheric radiation) and are very expensive, and relatively obtrusive.
A number of solutions have been proposed in order to resolve these problems. FR2965978, filed by the applicant, proposes a solution which makes it possible to significantly reduce the vertical dimensions of the antenna, thus making it possible to reduce installation costs and make the antenna less obtrusive. In addition, the antenna makes it possible to improve surface-wave propagation and to reduce ionospheric radiation. Nevertheless, the ionospheric radiation remains significant, in particular for angles of between ±[20°; 80° ] about the normal to the ground plane on which the antenna is arranged. This remaining ionospheric radiation can, in some frequency bands, produce fading phenomena, in particular when surface waves and space waves interfere with one another, in the region of the Earth's surface, after propagation in different media and via different routes.